/**
 * Copyright 2013-2015. blackdog1987@gmail.com . All rights reserved. 
 */
package com.gmail.blackdog1987.carcare.dao.hibernate.dialect;

import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.MappingException;
import org.hibernate.Hibernate;
import org.hibernate.dialect.Dialect;
import org.hibernate.dialect.function.VarArgsSQLFunction;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.exception.TemplatedViolatedConstraintNameExtracter;
import org.hibernate.exception.ViolatedConstraintNameExtracter;
import org.hibernate.util.StringHelper;

/**
 * @author DongGuoChao
 * @date 2013-12-26
 */
public class DualInformixDialect extends Dialect {

	/**
	 * Creates new <code>DualInformixDialect</code> instance. Sets up the JDBC /
	 * Informix type mappings.
	 */
	public DualInformixDialect() {
		super();

		registerColumnType(Types.BIGINT, "int8");
		registerColumnType(Types.BINARY, "byte");
		registerColumnType(Types.BIT, "smallint"); // Informix doesn't have a bit type
		registerColumnType(Types.CHAR, "char($l)");
		registerColumnType(Types.DATE, "date");
		registerColumnType(Types.DECIMAL, "decimal");
        registerColumnType(Types.DOUBLE, "float");
        registerColumnType(Types.FLOAT, "smallfloat");
		registerColumnType(Types.INTEGER, "integer");
		registerColumnType(Types.LONGVARBINARY, "blob"); // or BYTE
		registerColumnType(Types.LONGVARCHAR, "clob"); // or TEXT?
		registerColumnType(Types.NUMERIC, "decimal"); // or MONEY
		registerColumnType(Types.REAL, "smallfloat");
		registerColumnType(Types.SMALLINT, "smallint");
		registerColumnType(Types.TIMESTAMP, "datetime year to fraction(5)");
		registerColumnType(Types.TIME, "datetime hour to second");
		registerColumnType(Types.TINYINT, "smallint");
		registerColumnType(Types.VARBINARY, "byte");
		registerColumnType(Types.VARCHAR, "varchar($l)");
		registerColumnType(Types.VARCHAR, 255, "varchar($l)");
		registerColumnType(Types.VARCHAR, 32739, "lvarchar($l)");

		registerFunction( "concat", new VarArgsSQLFunction( Hibernate.STRING, "(", "||", ")" ) );
	}

	public String getAddColumnString() {
		return "add";
	}

	public boolean supportsIdentityColumns() {
		return true;
	}

	public String getIdentitySelectString(String table, String column, int type) 
	throws MappingException {
		return type==Types.BIGINT ?
			"select dbinfo('serial8') from dual" :
			"select dbinfo('sqlca.sqlerrd1') from dual";
	}

	public String getIdentityColumnString(int type) throws MappingException {
		return type==Types.BIGINT ?
			"serial8 not null" :
			"serial not null";
	}

	public boolean hasDataTypeInIdentityColumn() {
		return false;
	}

	/**
	 * The syntax used to add a foreign key constraint to a table.
	 * Informix constraint name must be at the end.
	 * @return String
	 */
	public String getAddForeignKeyConstraintString(
			String constraintName, 
			String[] foreignKey, 
			String referencedTable, 
			String[] primaryKey, boolean referencesPrimaryKey
	) {
		StringBuffer result = new StringBuffer(30);
		
		result.append(" add constraint ")
			.append(" foreign key (")
			.append( StringHelper.join(", ", foreignKey) )
			.append(") references ")
			.append(referencedTable);
		
		if(!referencesPrimaryKey) {
			result.append(" (")
			   .append( StringHelper.join(", ", primaryKey) )
			   .append(')');
		}

		result.append(" constraint ").append(constraintName);
			
			return result.toString();
	}

	/**
	 * The syntax used to add a primary key constraint to a table.
	 * Informix constraint name must be at the end.
	 * @return String
	 */
	public String getAddPrimaryKeyConstraintString(String constraintName) {
		return " add constraint primary key constraint " + constraintName + " ";
	}

	public String getCreateSequenceString(String sequenceName) {
		return "create sequence " + sequenceName;
	}
	public String getDropSequenceString(String sequenceName) {
		return "drop sequence " + sequenceName + " restrict";
	}

	public String getSequenceNextValString(String sequenceName) {
		return "select " + getSelectSequenceNextValString( sequenceName ) + " from dual";
	}

	public String getSelectSequenceNextValString(String sequenceName) {
		return sequenceName + ".nextval";
	}

	public boolean supportsSequences() {
		return true;
	}

	public boolean supportsLimit() {
		return true;
	}

	public boolean useMaxForLimit() {
		return true;
	}

	public boolean supportsLimitOffset() {
		return false;
	}

	public String getLimitString(String querySelect, int offset, int limit) {
		if (offset>0) throw new UnsupportedOperationException("informix has no offset");
		return new StringBuffer( querySelect.length()+8 )
			.append(querySelect)
			.insert( querySelect.toLowerCase().indexOf( "select" ) + 6, " first " + limit )
			.toString();
	}

	public boolean supportsVariableLimit() {
		return false;
	}

	public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter() {
        return EXTRACTER;
	}

	private static ViolatedConstraintNameExtracter EXTRACTER = new TemplatedViolatedConstraintNameExtracter() {

		/**
		 * Extract the name of the violated constraint from the given SQLException.
		 *
		 * @param sqle The exception that was the result of the constraint violation.
		 * @return The extracted constraint name.
		 */
		public String extractConstraintName(SQLException sqle) {
			String constraintName = null;
			
			int errorCode = JDBCExceptionHelper.extractErrorCode(sqle);
			if ( errorCode == -268 ) {
				constraintName = extractUsingTemplate( "Unique constraint (", ") violated.", sqle.getMessage() );
			}
			else if ( errorCode == -691 ) {
				constraintName = extractUsingTemplate( "Missing key in referenced table for referential constraint (", ").", sqle.getMessage() );
			}
			else if ( errorCode == -692 ) {
				constraintName = extractUsingTemplate( "Key value for constraint (", ") is still being referenced.", sqle.getMessage() );
			}
			
			if (constraintName != null) {
				// strip table-owner because Informix always returns constraint names as "<table-owner>.<constraint-name>"
				int i = constraintName.indexOf('.');
				if (i != -1) {
					constraintName = constraintName.substring(i + 1);
				}
			}

			return constraintName;
		}

	};

	public boolean supportsCurrentTimestampSelection() {
		return true;
	}

	public boolean isCurrentTimestampSelectStringCallable() {
		return false;
	}

	public String getCurrentTimestampSelectString() {
		return "select distinct current timestamp from dual";
	}
}